As shown in FIG. 1, in a conventional orthodontic treatment process, after part of the maxilla (or mandible) 10 is cut off or a tooth 12 is pulled out (usually not the incisor), the tooth 12 or the maxilla (or mandible) 10 is pulled and dragged by an orthodontic archwire 13 after the operation for helping the maxilla (or mandible) 10 to heal over or correcting the position of the tooth 12. In order to maintain the position of the orthodontic archwire 13 relative to the tooth 12, it is usually to apply several orthodontic brackets 14 adhered onto the tooth 12, and each orthodontic bracket 14 is arranged with slot 141 for providing an accommodation for the orthodontic archwire 13. The width and the depth of the slot 141 must be slightly larger than the diameter of the orthodontic archwire 13 such that, not only may the orthodontic archwire 13 be appropriately glided along the extensive direction of the slot 141, but also may the orthodontic archwire 13 be kept from being dropped out of the slot 141.
As known in the prior arts, in order to provide a pulling-and-dragging force to the orthodontic archwire 13, a screw 20 is screwed on a maxilla (or mandible) 10 at the adjacency of a molar 121, then a spring 15 or rubber band is further connected between the screw 20 and the end of the orthodontic archwire 13 for providing an appropriate pulling-and-dragging force. Since the end of this kind of spring 15 used specially for orthodontic treatment in current market is all arranged with a hook ring 151 so, for the connection between the spring 15 and the end of the orthodontic archwire 13, the end of the orthodontic archwire 13 just may be bent into a hook structure 131, then it can be easy to fit the hook ring 151 of the spring 15 into the hook structure 131 of the end of the orthodontic archwire 13, such that both connection is completed. Relatively, the connection between the spring 15 and the screw 20 is more difficult relatively.
As shown in FIG. 2 and FIG. 3, since the screw 20 currently applied for orthodontic treatment is all belonged to the common screw 20 as shown in FIG. 2 and FIG. 3, so the materials used for the screw 20, orthodontic bracket 14, and orthodontic archwire 13 are usually pure titanium alloy or stainless steel, those which are harmless to the human body. The screw 20 is commonly comprised of two parts: the head part 21 and the screw-body part 22. A general screw head groove 211 is then arranged on the head part 21 for providing a securing operation for a screwdriver (not shown in the figure). Usually, the dimension of the head part 21 is the widest part along the entire screw 20. Further, the diameter of the head part 21 is usually larger than the inner diameter of the hook ring 151 of the end of the spring 15, such that it is impossible for the spring to be hooked and hanged on the screw 20 directly. Therefore, for the current prior arts, an additional ligature wire 16 is used for tying the end of the spring 15 onto the screw-body part of the screw 20. However, such kind of method has caused several shortcomings as follows:
(1) It is difficult to operate. Since the head part 21 of the screw 20 is larger than the hook ring 151 of the spring 15, so it is impossible for the spring to be hooked and hanged on the screw 20 but, if the diameter of the head part 21 of this prior screw 20 is designed to be smaller than the hook ring 151 of the spring 15, then it will be much more easier for the spring 15 to be dropped off from the screw 20 to cause further inconvenience. Therefore, the prior arts that still use additional ligature wire 16 for tying the spring 15 and the screw 20 not only cause inconvenient in operation, but also cause difficulties for a less-experienced doctor to approach such kind of operation.
(2) It is easy for the spring 15 and the ligature wire 16 to impinge the gingiva 11. Since the ligature wire 16 is tied on the screw-body part 22 of the screw 20, so the ligature wire 16 and the spring 15 will be sometimes abutted against the gingiva 11 and irritate it. Not only will the user feel uncomfortable, but also may it sometimes hurt the gingiva 11 or reduce the healing-over speed of the wounds after operation.
(3) It is easy loosening for the screw 20. Since the screw-body part 22 of the screw 20 has a partial length that must be left in advance for tying the ligature wire 16 so, when the screw 20 is being driven tightly, it is impossible to screw the screw-body part 22 of the screw 20 completely into the maxilla (or mandible) 10 to make its head part 21 abutted smoothly against the maxilla (or mandible) 10. Contrarily, the head part 21 of the screw 20 must be kept an appropriate distance with the maxilla (or mandible) 10 for proceeding the operation of tying the ligature wire 16. In such way, the pulling-and-dragging force between the spring 15 and the ligature wire 16 will create a torque to the head part 21 of the screw 20, so it is easy to cause the screw 20 to loosen or even to drop off and break off.
(4) The gingiva 11 will be ugly after being healed over. Since the tissue of the gingiva 11 will be sometimes abutted against the screw 20 to grow during the healing procedure and there is a lack of appropriate guidance and restriction, so the surface of the gingiva 11 is uneven and ugly after being healing over.
(5) It only has a single function. This kind of prior screw 20 only can be applied in tying the ligature wire 16 for connecting the spring 15, neither does it have any other function, nor is it possible for providing an accommodation for the orthodontic archwire 13.
U.S. Pat. No. 4,988,292 discloses an abutment for orthodontic anchorage to a dental implant fixture. It comprises an endosseous implant fixture which is fixed in the lower jaw at the site of a missing molar for supporting an abutment for orthodontic anchorage. The abutment and the fixture are connected by a bolt in a detachable manner. However, the abutment of U.S. Pat. No. 4,988,292 does not provide the function of spring hooking. Even if someone tries to hook the spring on the abutment, the spring will be prone to impinge the gingival as previously illustrated. In addition, the fixture is prone to loose since it has identical outer threads and identical outer diameter throughout the entire fixture.
U.S. Pat. No. 5,836,768 discloses a fastening device for fixing orthodontic apparatuses on a dental implant. It comprises an implant which is fixed in the jaw bone, an anchoring screw screwed within an axially arranged threaded bore in the implant, and an occlusal screw located inside the threaded bore and engaged with the anchoring screw. None part of the occlusal screw nor anchoring screw is exposed outside the implant, such that they cannot be used for spring hooking. Even if the spring can be tied (not hook) on a bracket of U.S. Pat. No. 5,836,768, the spring will be prone to impinge the gingival. In addition, the implant is prone to loose since it has identical outer threads and identical outer diameter.
U.S. Pat. No. 5,921,774 discloses a supporting body for use in orthodontic appliance. It comprises a supporting body to be fixed in the jaw bone, an abutment formed with an arm at a side surface thereof, and a male screw for screwing and fixing the abutment onto the top of the supporting body. Since the screw is an independent element and is screwed from a top side of the abutment, therefore the arm can only be form at the side surface of the abutment, and thus the application and flexibility thereof are limited. In addition, the device disclosed by U.S. Pat. No. 5,921,774 comprises at least three elements (e.g., supporting body, abutment and male screw). Not only the cost to manufacture is higher, but also is more complex to use. Moreover, the supporting body is prone to loose since it has identical outer threads (or no threads at all) and identical outer diameter throughout the entire supporting body.
Other prior art, such like U.S. Pat. No. 6,241,516, U.S. Pat. No. 5,071,345, and US Pub. No. 2002/0127510. None of them has been disclosed a screw device which comprises a screw-body part, a platform part and a head part which is detachable from and exposed outside the platform part (or screw-body part) and is operatable to hook the spring for orthodontic treatment.
As known from above description, the prior arts that are used for orthodontic treatment currently still have many shortcomings to be further improved urgently.